Composite prepreg and fiber-reinforced plastic molded body

Abstract

A composite prepreg and a fiber-reinforced plastic molded body are described that are excellent in secondary weldability with another member and exhibit excellent handleability and reinforcing characteristics, where the composite prepreg in which reinforcing fibers are impregnated with a thermoplastic resin and a thermosetting resin, and a thermoplastic resin layer and a thermosetting resin layer that form an interface and joined to each other are formed, wherein the thermoplastic resin layer is present on at least one surface of the composite prepreg, and the thermoplastic resin layer contains continuous reinforcing fibers.

1 . A composite prepreg in which reinforcing fibers are impregnated with a thermoplastic resin and a thermosetting resin, and a thermoplastic resin layer and a thermosetting resin layer that form an interface and are joined to each other are formed,
 wherein the thermoplastic resin layer is present on at least one surface of the composite prepreg, and the thermoplastic resin layer contains continuous reinforcing fibers,   reinforcing fibers are distributed in a region of 80% or more of a thickness of each layer of the thermoplastic resin layer and the thermosetting resin layer in a cross section perpendicular to a plane direction, and   an adhesion strength between the thermoplastic resin layer and the thermosetting resin layer is 1 N/24 mm or more.   
     
     
         2 . The composite prepreg according to  claim 1 , wherein a volume content of the reinforcing fibers in the thermoplastic resin layer is 10% or more. 
     
     
         3 . The composite prepreg according to  claim 1 , wherein a coefficient of variation Q for a fiber content of the reinforcing fibers per unit section of 0.05 mm square in the thermoplastic resin layer is 40% or less. 
     
     
         4 . The composite prepreg according to  claim 1 , wherein the reinforcing fibers are carbon fibers. 
     
     
         5 . The composite prepreg according to  claim 1 , wherein the thermosetting resin layer contains continuous reinforcing fibers. 
     
     
         6 . The composite prepreg according to  claim 1 , wherein as the reinforcing fibers contained in the thermoplastic resin layer, reinforcing fibers having a surface free energy of 10 to 50 mJ/m 2  as measured by a Wilhelmy plate method are used. 
     
     
         7 . The composite prepreg according to  claim 1 , wherein in the thermoplastic resin layer and the thermosetting resin layer, reinforcing fibers oriented in one direction are present in a form of being arranged in one layer or a plurality of layers. 
     
     
         8 . The composite prepreg according to  claim 1 , wherein the reinforcing fibers contained in the thermoplastic resin layer and the thermosetting resin layer are the same. 
     
     
         9 . The composite prepreg according to  claim 1 , wherein when a cross section that forms an angle of 45 degrees with respect to an orientation direction of the continuous reinforcing fibers and is perpendicular to the plane direction of the prepreg is observed, a curve formed by an interface between the thermosetting resin layer and the thermoplastic resin in the cross section has a roughness average length RSm of 100 μm or less and a roughness average height Rc of 3.5 μm or more defined by JIS B0601 (2013). 
     
     
         10 . A method for producing a composite prepreg, the method comprising:
 stacking a thermosetting prepreg in which reinforcing fibers are impregnated with a thermosetting resin to a thermoplastic semipreg in which continuous reinforcing fiber are impregnated with a thermoplastic resin with an unimpregnated region left on a surface thereof, in such a manner that the thermosetting prepreg is in contact with the unimpregnated region of the thermoplastic semipreg; and   heating and pressurizing the thermosetting prepreg and the thermoplastic semipreg.   
     
     
         11 . A method for producing a composite prepreg, the method comprising:
 stacking a thermosetting prepreg in which reinforcing fibers are impregnated with a thermosetting resin to a thermoplastic prepreg in which continuous reinforcing fibers are impregnated with a thermoplastic resin having a melting temperature of 180° C. or less; and   heating and pressurizing the thermosetting prepreg and the thermoplastic prepreg.   
     
     
         12 . A fiber-reinforced plastic molded body in which reinforcing fibers are impregnated with a thermoplastic resin and a thermosetting resin, and a thermoplastic resin layer and a thermosetting resin layer that form an interface and are joined to each other are formed,
 wherein the thermoplastic resin layer is present on at least one surface of the fiber-reinforced plastic molded body, and the thermoplastic resin layer contains continuous reinforcing fibers, and   reinforcing fibers are distributed in a region of 80% or more of a thickness of each of the thermoplastic resin layer and the thermosetting resin layer in a cross section perpendicular to a plane direction, and an adhesion strength between the thermoplastic resin layer and the thermosetting resin layer is 1 N/24 mm or more.